irrelevant -
having no bearing on or connection with the subject at issue; "an irrelevant comment"; "irrelevant allegations"
relevant having a bearing on or connection with the subject at issue; "the scientist corresponds with colleagues in order to learn about matters relevant to her own research"
digressive,
tangential (of e.g. speech and writing) tending to depart from the main point or cover a wide range of subjects; "amusingly digressive with satirical thrusts at women's fashions among other things"; "a rambling discursive book"; "his excursive remarks"; "a rambling speech about this and that"
